Globalisation, if left unmanaged, is a threat to Britain's national security. This is a bald statement, but it is true, and we would be better off as a country if its veracity were more widely accepted and its implications more fully understood. Globalisation may have brought huge benefits to millions of people around the world but it has simultaneously exposed us to new hazards that we are not well placed to meet. We need a new approach aimed squarely at the management of a world in which power is slipping beyond the control of states.

Today's security agenda is often presented as a long list of threats: international terrorism, transnational crime, the threat of a new pandemic, energy insecurity and the dangers of climate change. These are all pressing issues but it is too easy to present them as disparate and unconnected.

The fact is that transnational crime has not gone transnational by accident but as a direct by-product of the increased flows of goods, services and people in the mainstream economy. Terrorism has not become a bigger concern just because of the rise of jihadist groups but because global communications and the diffusion of knowledge and technology have extended the organisational reach and increased the destructive potential of even small numbers of people. The pandemic threat is not so serious just because of the possibility of a disease outbreak but because, in a world of people moving on this scale, a disease could be upon us long before we know it is even there.

The binding theme in all this is the interdependence that comes with globalisation: the extent to which we are all connected, reliant upon and vulnerable to each other, just about wherever we live on the planet. No issue is more emblematic of this than climate change, which may yet become a contributing factor to population displacement and societal conflicts around the world. And no issue is more symbolic of its realities than energy security, where the UK faces concerns over both the security and price of our increasingly international energy supply.

This is not a temporary state of affairs but a permanent one and an interdependent world is a world of shared destinies, where insecurities in one part of the world can quickly affect security in another. In this environment no state, no matter how powerful, can meet its security needs alone. Nor is the security front line any respecter of borders. The front line in the battle for security now exists simultaneously in the battlefields of Afghanistan, in the fragile states of Africa and the Middle East, in our public health arrangements to deal with biothreats and in our attempts to counter radicalisation.

In response to this we need a new era of multinational institution- building, and a deepened level of security and defence collaboration inside the EU. On both, we need to match the talking with action.

There is clearly a need for the Security Council to be reformed, to bring in new permanent members such as India, Brazil and South Africa. This would make it more reflective of today's world. We shouldn't, however, stop reform of the UN - or perhaps even start it - with the Security Council itself. There are other, more realistic goals. The UN needs to be seen more as an important conferrer of legitimacy on international action, rather than always as the implementer of action itself. It needs to direct additional financial and logistical support to regional organisations, such as the African Union, particularly in conflict prevention and the provision of well-trained and equipped peacekeeping forces. We should also reinforce important UN agencies such as the World Health Organisation.

Beyond the UN, we need a new era of treaty-based action. What we have in mind here is not John McCain's idea of a League of Democracies, which has a “return to the Cold War” mentality written all over it, but a more issue-based approach that strengthens treaties and institutions that already exist to address specific challenges. Examples here include the nuclear non-proliferation treaty, the International Atomic Energy Agency, the International Criminal Court and a post-Kyoto climate change framework. We also need to create new treaties and multilateral institutions to support them, to deal with issues such as global energy co-ordination, internet crime, terrorism and small arms.

In Europe there is no area of threat that couldn't be more effectively addressed through deeper collaborative effort. The EU is learning how to use elements of soft power to promote European interests abroad and to promote stability in the wider European neighbourhood. But multilateral co-operation at European level must also involve greater defence co-operation if it is to be taken seriously. The drive to create EU battle groups should be accelerated, made fully compatible with Nato response forces and should form the basis of an emerging European counter-insurgency capacity capable of operating in failed states and post-conflict environments. This will be vital if we are called upon by the UN or others to extend public authority into some of the ungoverned spaces that globalisation is helping to generate.

We also need improved EU intelligence co-operation to combat terrorism and organised crime, the creation of integrated EU special forces, and a serious increase in gendarmerie forces. But even this will not be enough. The EU nations don't just need collaboration on new formations, they need to spend money on the right kit, on the right numbers of troops with the right training to handle today's complex missions; and above all they need to be prepared to use it all. This means more collaboration in defence planning and procurement - to make the European whole greater than the sum of the national parts, but it also means far greater political will than has been on show so far.

For the first time in more than 200 years we are moving into a world not wholly dominated by the West. If we want to influence this environment rather than be held to ransom by it, and if we want to take hold of some of the worrying features of globalisation, then real, practical multilateralism is a strategic necessity, not a liberal nicety.

Lord Robertson of Port Ellen is a former General-Secretary of Nato, and Lord Ashdown of Norton-sub-Hamdon was the High Representative of the International Community in Bosnia & Herzegovina. They are co-chairmen of the IPPR Commission on National Security in the 21st century.

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